/****************************************************************************
 * Copyright (c) 2018 ~ 2020.10 liangxie
 * 
 * https://qframework.cn
 * https://github.com/liangxiegame/QFramework
 * https://gitee.com/liangxiegame/QFramework
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 ****************************************************************************/

using System;

namespace QFramework
{
    /// <summary>
    /// 事件注入,和 NodeSystem 配套使用
    /// </summary>
    /// <typeparam name="T"></typeparam>
    public class EventInjector<T>
    {
        public delegate bool InjectEventTrigger(T lastValue, T newValue);

        public delegate T InjectEventGetter();

        private T mCahedLastValue;

        public readonly Func<T> mGetter;

        public T Value
        {
            get { return mCahedLastValue; }
        }

        public EventInjector(Func<T> getter)
        {
            mGetter = getter;
        }

        public bool GetOn(InjectEventTrigger triggerConditionWithOldAndNewValue)
        {
            var value = mGetter();
            var trig = triggerConditionWithOldAndNewValue(mCahedLastValue, value);
            mCahedLastValue = value;
            return trig;
        }

        public bool GetOnValueChanged(Func<T, bool> triggerConditionWithNewValue = null)
        {
            return GetOn((lastValue, newValue) =>
                lastValue.Equals(newValue) &&
                (triggerConditionWithNewValue == null || triggerConditionWithNewValue(newValue)));
        }
    }
}